Generally, the manufacturing process of a semiconductor device includes a series of processing steps of: applying photoresist to a semiconductor wafer or the like as a substrate-to-be-processed (hereinafter referred to as a “wafer or the like”); printing an image of a circuit pattern on the photoresist; and then removing the photoresist from the wafer or the like.
In the above-mentioned processing, if an oxide film on the surface of a wafer or the like is removed by etching with a chemical liquid, dilute hydrofluoric acid (DHF) for example, the surface of the wafer or the like will become hydrophobic. Consequently, watermarks tend to be generated in a case that the wafer or the like proceeds to cleaning processing and drying processing without any other processing in between, which leads to a possible yield loss. Hydrophilization is then conducted by forming an oxide film on the surface of the wafer or the like so that the surface will have a hydrophilic character. A known method to form an oxide film is immersing a substrate in ozone water. A thinner oxide film is preferred to be formed as long as the oxide film has an enough thickness to prevent water mark generation.
However, the problem is that uniformity of the film thickness would be reduced by the conventional substrate processing method. A thin oxide film with a uniform thickness therefore could not be formed.